MnCl2 = Cl2 + Mn

MnCl_2 manganese(II) chloride ⟶ Cl_2 chlorine + Mn manganese

Balance the chemical equation algebraically: MnCl_2 ⟶ Cl_2 + Mn Add stoichiometric coefficients, c_i, to the reactants and products: c_1 MnCl_2 ⟶ c_2 Cl_2 + c_3 Mn Set the number of atoms in the reactants equal to the number of atoms in the products for Cl and Mn: Cl: | 2 c_1 = 2 c_2 Mn: | c_1 = c_3 Since the coefficients are relative quantities and underdetermined, choose a coefficient to set arbitrarily. To keep the coefficients small, the arbitrary value is ordinarily one. For instance, set c_1 = 1 and solve the system of equations for the remaining coefficients: c_1 = 1 c_2 = 1 c_3 = 1 Substitute the coefficients into the chemical reaction to obtain the balanced equation: Answer: | | MnCl_2 ⟶ Cl_2 + Mn

⟶ +

manganese(II) chloride ⟶ chlorine + manganese

| manganese(II) chloride | chlorine | manganese molecular enthalpy | -481.3 kJ/mol | 0 kJ/mol | 0 kJ/mol total enthalpy | -481.3 kJ/mol | 0 kJ/mol | 0 kJ/mol | H_initial = -481.3 kJ/mol | H_final = 0 kJ/mol | ΔH_rxn^0 | 0 kJ/mol - -481.3 kJ/mol = 481.3 kJ/mol (endothermic) | |

Construct the equilibrium constant, K, expression for: MnCl_2 ⟶ Cl_2 + Mn Plan: • Balance the chemical equation. • Determine the stoichiometric numbers. • Assemble the activity expression for each chemical species. • Use the activity expressions to build the equilibrium constant expression. Write the balanced chemical equation: MnCl_2 ⟶ Cl_2 + Mn Assign stoichiometric numbers, ν_i, using the stoichiometric coefficients, c_i, from the balanced chemical equation in the following manner: ν_i = -c_i for reactants and ν_i = c_i for products: chemical species | c_i | ν_i MnCl_2 | 1 | -1 Cl_2 | 1 | 1 Mn | 1 | 1 Assemble the activity expressions accounting for the state of matter and ν_i: chemical species | c_i | ν_i | activity expression MnCl_2 | 1 | -1 | ([MnCl2])^(-1) Cl_2 | 1 | 1 | [Cl2] Mn | 1 | 1 | [Mn] The equilibrium constant symbol in the concentration basis is: K_c Mulitply the activity expressions to arrive at the K_c expression: Answer: | | K_c = ([MnCl2])^(-1) [Cl2] [Mn] = ([Cl2] [Mn])/([MnCl2])

Construct the rate of reaction expression for: MnCl_2 ⟶ Cl_2 + Mn Plan: • Balance the chemical equation. • Determine the stoichiometric numbers. • Assemble the rate term for each chemical species. • Write the rate of reaction expression. Write the balanced chemical equation: MnCl_2 ⟶ Cl_2 + Mn Assign stoichiometric numbers, ν_i, using the stoichiometric coefficients, c_i, from the balanced chemical equation in the following manner: ν_i = -c_i for reactants and ν_i = c_i for products: chemical species | c_i | ν_i MnCl_2 | 1 | -1 Cl_2 | 1 | 1 Mn | 1 | 1 The rate term for each chemical species, B_i, is 1/ν_i(Δ[B_i])/(Δt) where [B_i] is the amount concentration and t is time: chemical species | c_i | ν_i | rate term MnCl_2 | 1 | -1 | -(Δ[MnCl2])/(Δt) Cl_2 | 1 | 1 | (Δ[Cl2])/(Δt) Mn | 1 | 1 | (Δ[Mn])/(Δt) (for infinitesimal rate of change, replace Δ with d) Set the rate terms equal to each other to arrive at the rate expression: Answer: | | rate = -(Δ[MnCl2])/(Δt) = (Δ[Cl2])/(Δt) = (Δ[Mn])/(Δt) (assuming constant volume and no accumulation of intermediates or side products)

| manganese(II) chloride | chlorine | manganese formula | MnCl_2 | Cl_2 | Mn Hill formula | Cl_2Mn | Cl_2 | Mn name | manganese(II) chloride | chlorine | manganese IUPAC name | dichloromanganese | molecular chlorine | manganese

| manganese(II) chloride | chlorine | manganese molar mass | 125.8 g/mol | 70.9 g/mol | 54.938044 g/mol phase | solid (at STP) | gas (at STP) | solid (at STP) melting point | 652 °C | -101 °C | 1244 °C boiling point | | -34 °C | 1962 °C density | 2.98 g/cm^3 | 0.003214 g/cm^3 (at 0 °C) | 7.3 g/cm^3 solubility in water | | | insoluble